Polybutylene pipe and tubing is now fabricated by extrusion technology and such tubing is finding wide application in hot and cold water plumbing. Various types of fittings are employed with such polybutylene tubing, one example being that shown in applicant's prior U.S. Pat. No. 4,316,870 wherein the tubing end is reshaped to provide a conical or spherical end and flange, the tubing end then being connected to a conventional fitting for plastic or copper plumbing. However, for other types of fittings, different forms of connections are required.
Another example of a fitting and process for making that fitting is shown in Canadian Pat. No. 684,896 issued Apr. 21, 1964 to Montecatini. The process disclosed in such Canadian patent involves the steps of cross-linking at least one end of the pipe by impregnating the pipe end with an organic peroxide and also applying heat thereto. After the tubing end is inserted on a coupling member, the entire coupling is then further heated to a higher temperature than the melting point of the uncrosslinked plastic polymeric material. Such a process is time consuming and hard to control and is usually not suitable if the coupling member itself is of a plastic material.